Privacy Protocols

Privacy Architecture: Monero/Zcash-Grade Anonymity

SilverBitcoin implements mandatory privacy on all transactions using multiple complementary protocols. Unlike Bitcoin (no privacy) and Zcash (optional privacy), SilverBitcoin makes privacy mandatory on every single transaction.

1. Lelantus Protocol

1.1 Overview

Lelantus provides Direct Anonymous Payments (DAP) with coin history privacy. It's inspired by Zcash's Sapling protocol but with enhanced privacy guarantees.

1.2 Key Features

• Direct Anonymous Payments (DAP): Transactions don't reveal sender or receiver
• Coin History Privacy: Previous transaction history is hidden
• Efficient Zero-Knowledge Proofs: Scalable privacy without trusted setup
• Multiple Privacy Levels: Standard, Enhanced, Maximum
• JoinSplit Transactions: Multi-input/output privacy with range proofs

1.3 Technical Components

• Pedersen Commitments: Cryptographic commitments to coin values
• Accumulator: Efficient membership proofs for coin history
• Witness Management: Performance optimization for large accumulators
• Zero-Knowledge Proofs: Prove transaction validity without revealing amounts
• Range Proofs: Prove amounts are in valid range (0 to 2^64)

1.4 Privacy Guarantees

• Sender Privacy: ✅ Hidden among accumulator members
• Receiver Privacy: ✅ Hidden via stealth addresses
• Amount Privacy: ✅ Hidden via range proofs
• Coin History Privacy: ✅ Previous transactions hidden

2. Mimblewimble Protocol

2.1 Overview

Mimblewimble provides confidential transactions with extreme scalability. Transaction amounts are hidden, and old transactions can be pruned from the blockchain.

2.2 Key Features

• Confidential Transactions: Transaction amounts are hidden
• Compact Representation: Transactions are extremely compact
• Extreme Scalability: Old transactions can be pruned
• Privacy Without Trusted Setup: No ceremony required
• UTXO Pruning: Reduces blockchain size dramatically

2.3 Technical Components

• Pedersen Commitments: Commitments to transaction amounts
• Range Proofs: Prove amounts are in valid range
• Transaction Kernels: Metadata and signatures
• Block Structure: Transaction aggregation for compactness
• Efficient State Management: Pruning old transactions

2.4 Scalability Benefits

• Blockchain Size: 90%+ reduction compared to Bitcoin
• Verification Speed: Faster due to smaller transaction size
• Pruning: Old transactions can be safely removed
• Archival Nodes: Only need to store recent history

3. Stealth Addresses

3.1 Overview

Stealth addresses provide recipient privacy by generating a unique address for each transaction. The recipient can recover the address using their private key, but observers cannot link transactions to the same recipient.

3.2 Workflow

1. Recipient publishes stealth address (public key)
2. Sender generates ephemeral keypair
3. Sender derives unique address using SHA-512
4. Sender sends to derived address
5. Recipient can recover address using private key

3.3 Privacy Guarantees

• Recipient Privacy: ✅ Each transaction uses unique address
• Address Unlinkability: ✅ Transactions cannot be linked to same recipient
• Quantum Resistance: ✅ SHA-512 based derivation
• Standard Format: ✅ SLVR prefix for privacy transactions

4. Ring Signatures

4.1 Overview

Ring signatures provide sender privacy by hiding the sender among a ring of 16 members. The signature proves that one of the ring members signed the transaction, but doesn't reveal which one.

4.2 Key Features

• Sender Privacy: Sender hidden among 16 ring members
• Key Image Double-Spend Prevention: Prevents double-spending
• Deterministic Signature Generation: Reproducible signatures
• Real Cryptographic Implementation: Production-ready code

4.3 Workflow

1. Sender selects 16 ring members (including themselves)
2. Sender creates ring signature
3. Signature proves one member signed, but doesn't reveal which
4. Key image prevents double-spending
5. Observers cannot determine sender

4.4 Privacy Guarantees

• Sender Privacy: ✅ Hidden among 16 members
• Linkability Prevention: ✅ Key image prevents linking
• Unforgeability: ✅ Only ring member can create signature
• Anonymity Set: ✅ 16 members provides strong privacy

5. Bulletproofs+

5.1 Overview

Bulletproofs+ provide efficient range proofs for amount privacy. They prove that transaction amounts are in a valid range (0 to 2^64) without revealing the actual amounts.

5.2 Key Features

• Amount Privacy: Transaction amounts are hidden
• Efficient Proofs: ~700 bytes per transaction
• Batch Verification: Multiple proofs verified efficiently
• No Trusted Setup: No ceremony required
• Logarithmic Size: Proof size grows logarithmically with range

5.3 Privacy Guarantees

• Amount Privacy: ✅ Amounts hidden from observers
• Validity Proof: ✅ Amounts proven to be in valid range
• No Inflation: ✅ Prevents creation of money
• Efficiency: ✅ Minimal overhead compared to transparent transactions

6. Privacy Comparison

7. Privacy Guarantees

7.1 Sender Anonymity

SilverBitcoin provides sender anonymity through ring signatures. The sender is hidden among 16 ring members, making it computationally infeasible to determine the actual sender.

7.2 Receiver Anonymity

SilverBitcoin provides receiver anonymity through stealth addresses. Each transaction uses a unique address, making it impossible to link transactions to the same recipient.

7.3 Amount Privacy

SilverBitcoin provides amount privacy through Bulletproofs+ and Mimblewimble. Transaction amounts are hidden from observers while still being verifiable.

7.4 Coin History Privacy

SilverBitcoin provides coin history privacy through Lelantus. Previous transaction history is hidden, preventing analysis of coin origins.

8. Implementation Status

• ✅ Lelantus Protocol: Production-ready (24 tests passing)
• ✅ Mimblewimble Protocol: Production-ready
• ✅ Stealth Addresses: Production-ready
• ✅ Ring Signatures: Production-ready
• ✅ Bulletproofs+: Production-ready
• ✅ Mandatory Privacy: All transactions private by default